1. Field of the Invention
The present invention relates to semiconductor devices and, more particularly, to a semiconductor device, such as a capacitor, having enhanced electrical characteristics. The invention also relates to a method for manufacturing the same.
2. Description of the Related Art
To increase the integration density of semiconductor devices, various methods have been employed. These methods include reducing the thickness of a gate or capacitor dielectric layer, or forming a high-k dielectric layer, for example, to increase capacitance. Unfortunately, although reducing the dielectric layer thickness increases the capacitance, it also significantly increases leakage current. In addition, forming a high-k dielectric layer often requires the use of a metal electrode, because a conventional polysilicon electrode causes problems such as tunneling and increases leakage current. In the case of such a metal-insulator-metal (MIM) capacitor with a high-k dielectric layer, due to a high-speed dielectric growth process typically required for mass production, the high-k dielectric layer suffers from a substantial amount of oxygen non-stoichiometry. Thus, a thermal process in an oxygen ambient is needed to stabilize the stochiometry in the lack of oxygen to cure defects occurring in the dielectric layer during the deposition or to remove impurities present in the dielectric layer. When such a thermal process is performed, however, oxygen atoms react with an electrode, thereby growing an unnecessary oxide layer that reduces capacitance.
To avoid the oxidation, the thermal process may be performed in a low-concentration oxygen ambient, or in an inert gas (e.g., N2 or Ar) ambient. This process is, however, ineffective to remove impurities, such as carbon, present in the dielectric layer. Furthermore, thermo-mechanical stresses generated between the electrode and the dielectric layer during the high-temperature thermal process increase leakage current and further increase contact resistance.
Accordingly, there is an immediate need for novel thermal processing techniques to deal with problems such as described above.